Sunday, January 29, 2012

JavaScript Pointer Lock (Mouse Lock) in Chrome Developer Preview

Mouse Lock is the canonical term for when a game (or other application) removes the mouse cursor from view and interprets mouse motion for something else, e.g. looking around in a 3D world. To date this has not been possible for web applications without a plugin, which makes many game genres and other applications just terrible to use. (e.g. forcing users to drag the mouse button to pan the view, while a native application would use the mouse button for something else, e.g. interacting with the world.).

Today the first Chrome Canary build is available to try the feature out:

Get a build.

Chrome Canary builds auto-update daily and install without interfering with your normal installation of Chrome, they're the way to go since they're so easy. Unless your on Linux, where you need to just get a recent Linux Build.

There's a lot that will be changing with this. First, I have several issues still to deal with in the WebKit implementation, a security review will certainly find more, and oh yeah we're going to overhaul the spec to be as identical as possible to the Fullscreen spec.

Some have asked if pointer lock will be forever restricted to fullscreen mode. No, in fact by the time the JavaScript bindings ship without developer flags I'm hoping to have removed the restriction, and if not then soon after. The only real requirement is that the user not suffer from a poorly behaving website. At the moment that means if a site spams lock requests that we require a user-gesture (e.g. clicking on the web page content, or pressing a key). Fullscreen currently requires the same, so we hide in it's shadow, but I'll implement the check even in windowed mode.

Chrome 19 is the earliest JavaScript pointer lock could ship without a developer flag, but it's predicated on many things coming into place. However, Native Client apps have been able to use it since Chrome 16.